llllllllllllllllllllllllllllllllllIlllllllllllllllllllllllllllllll LOS ALAMOSNATIONALLABORATORY. USO05160696A PATENTS REPRESENTING LOS ALAMOS 19] [1I] Patent Number: 5,160,696 - RESEARCH [45] Date of Patent: Nov. 3, 1992
[54] APPARATUS FOR NUCLEAR Source,” proceedings of the International Collaboration TRANSMUTATION AND POWER on Advanced Neutron sources held on Sep. 13-16, PRODUCTION USING ANINTENSE 1983, Atomic Energy of Canada, Limited, Report AE- ACCELERATOR-GENERATED THERiiAL CL-8488. NEUTRON FLUX “Preliminary Design and Neutronic Analysis ofa Laser [75] Inventor: Charles D. Bowman, Los Alamos, N. Fusion Driven Actinide Waste Burning Hybrid Reac- Mex. tor”, Berwald et al., Nuclear Technology, vol. 42, Jan. 1979, pp. 34-50. [73] Assignee: Tbe United States of Ameriea as “Intense Neutron Sources”, U.S. Atomic Energy Com- represented by the United States mission, COMF-660925, Sep. 1966, pp. 651-652. Department of Energy, W=hington, D.C. Primary Examiner-Brooks H. Hunt [21] Appl. No.: 564),900 As.risfant Examiner—Frederick H. Voss Attorney, Agent, or Firm—Samuel M. Freund; Paul D. [22] Filed: Jul. 17, 1990 Gaetjens; William R. Moser [51] Int. Cl,s ...... G21G 1/02 [52] U.S. Cl...... 376/189; 376/195; [57] ABSTRA~ 376/170 Apparatus for nuclear transmutation and power pro- [58] Field of Search ...... 376/189-195, duction using an intense accelerator-generated thermal 376/170-172, 156, 158, 354-360 neutron flux. High thermal neutron fluxes generated [56] References Cited from the action of a high power proton accelerator on a spallation target allows the eff)cient bum-up of higher U.S. PATENT DOCUMENTS actinide nuclear waste by a two-step process. Addition- 3,216,901 11/1965 Teitel ...... 376/359 ally, rapid bum-up of fission product waste for nuclides 3,325,371 6/1967 Stanton having small thermal neutron cross sections, rmd the 3,349,001 10/1967 Stanton . practicality of small material inventories while achiev- 3,453,175 7/1969 Hedge 3,778,627 12/1973 Carpenter ing significant throughput derive from employment of 4,309,249 1/1982 S!einberg et al. such high fluxes. SeveraI nuclear technology problems 4,721,596 1/1988 Marriott et al...... 376/189 are addressed including 1. nuclear energy production without a waste stream requiring storage on a geologi- FOREIGN PATENT DOCUMENTS cal timescale, 2. the bum-up of defense and commercial 98600 4/1988 Japan ...... 376/158 nuclear wrote, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target OTHER PUBLICATIONS for neutron production surrounded by a blanket region H. Takada et al., ‘“A Conceptual Study of Aclinide for transmutation, a turbine for electric power produc- Transmutation System with Proton Accelerator,” pro- tion, and a chemical processing facility. In all applica- ceedings of the 2nd International Symposium held on tions, the accelerator power may be generated inter- Jan. 24-26, Mite, Ibaraki, Japan. nally from fission and the waste produced thereby is “Accelerate Molten-Salt Kazuo Furukawa et al., transmuted internally so that waste management might Breeding and Thorium Fuel Cycle,” proceedings of the not be required beyond the human lifespan. 2nd International Symposium held on Jan. 24-26, Mite, Ibaraki, Japan. F. Atchison et al., “Status Report of the SIN Neutron 60 Cfaims, 4 Drawing Sheets 10 ——————.————— -——- ————. - > —-————— ---- -———— --- I 1 I lz~ I I
I -1 I&Xl MeV
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Fig. 1 . High Intensity Spallation Neutron Radioactive Wastes Source and Dilute Defense or Commercial Blanket Concept -——— ———— —- 1 F+ <10 1- i t I I I 1.6 GeV Accelerator Advanced Fluoride I Chemical Partitioning I I and Processing I I 3 I 50
All wl “- Fig. 2 U.S. Patent Nov. 3, 1992 Sheet 3 of 4 5,160,696
Em{ A T1/2 = 2.1 Days T1/2 = 2.4 Days
237 h@ 238 h@ 239 h@ f= v 1 242Am f = 6950 -J C=lloo h . Fig. 3 c ~ —. —. —— —— —— —— —— .— 1 “m I I MS Heat Exchanaer\ a’ grq 44, I Isotope Extraction and Feed 40 -+ I f% I Pb-Bi Heat I Exchanger * Molten Fission ’84 86 Salt Product Bundle I K!J--d90 92> ul “ I -— —— —— —— —— —— –-J Fig. 4 5.160.696 1 2 since the thorium is mixed with lithium fluoride, proton APPARATUS FOR NUCLEAR TRANSMUTATION spallation will again produce bothersome tars. AND POWER PRODUCTION USING AN INTENSE In “Status Report Of The SIN Neutron Source,” by ACCELERATOR-GENERATED THERMAL F. Atchison and W. E. Fischer, Proceedings Of Intern- NEUTRON FLUX 5 ational Collaboration On Advanced Neutron Sources (ICANS-VII), Sep. 13-16, 1983, Atomic Energy Of BACKGROUND OF THE INVENTION Canada, Limited, Report AECL-8488, the authors dis- close a low-power target for low flux neutron produc- The present invention relates generally to a resolu- tion in Pb-Bi from neutron bombardment with subse- tion of the waste problem associated with the various 10 quent neutron therrnalization using heavy water. Heat is fission-based technologies by waste transmutation using removed from the target by thermal convection, and an accelerator-generated intense thermal neutron flux, the low power levels also permit the use of a window and more particularly to the reduction in the period for between the acderator vacuum and the target. The management of existing commercial and defense nu- proton beam strikes the target from below which has clear waste to a time period comparable to the human 15 advantages for the thermrd convection cooling. life.spamand allows future production of nuclear power Accordingly, it is an object of the present invention and material without generation of wastes requiring to efficiently transmute higher actinides and other nu- long term storage. The apparatus has significant opera- clear wastes. tional safety advantages over existing technology since Another object of my invention is to generate power it operates well below nuclear criticality and with a 20 from fertile materials while transmuting the fission and greatly reduced inventory of radioactive nuclear mate- other waste in order to avoid long-term storage. rial. The United States Government has rights in this Yet another object of the present invention is to gen- invention pursuant to Contract No. W-7405-EXG-36 erate tritium drawing on an external electric power between the Department of Energy and the University source, and without generation of waste requiring long- of California. 25 term storage. Present nuclear waste strategies, centered aboul geo- logic repository storage, require geologic stability and SUMMARY OF THE INVENTION separation of wastes from human contact for tens of To achieve the foregoing and other objects and in thousands of years. Transmutation offers the potential accordance w’ith the purpose of the present invention, for transforming the time scales associated with such 30 as embodied and broadly described herein, the appara- storage to hundreds of years or less. tus for generating power from fertile nuclear materials Transmutation of long-lived nuclear wastes to short- and transmuting wastes therefrom to less radioactive lived or stable isotopes has been studied for many years. species may include a source of high intensity, high-en- A sampling of illustrative techniques was presented in a ergy beam of protons, a liquid-metal spallation target recent symposium in a presentation entitled “A Concep- 35 having an upwardly facing open surface for producing tual Study Of Actinide Transmutation System With a high neutron flux upon being impacted by high-en- Proton Accelerator(1) Target Neutronics Calculation,” ergy protons, a substantially gas-tight enclosure sur- by H. Takada, 1. Kanno, T. Takizuka, T. Ogawa, T. rounding the spallation target, windowless apparatus Nishida, and Y. Kaneko, Proceedings Of The 2nd Inter- for directing the beam of protons onto the open surface national Symposium On Advanced Nuclear Energy 40 of the spallation target, a neutron moderator for ther- Research-Evolution By Accelerators, January 24-26, malizing neutrons generated from the spallation target, 1990, Mite, Ibaraki, Japan. The authors describe a trans- a container for holding fertile nuclear material located mutation apparatus using keV neutrons which requires within the neutron moderator and spaced apart from large material inventones to achieve significant trans- and outside of the spallation target, and a container for mutation rates since cross sections for neutron capture 45 holding materials to be transmuted located within the are small at these neutron energies. Moreover, the pro- neutron moderator and spaced apart and outside of the ton beam is admitted to the subcritical reactor target spallation target, yet closer thereto than the fertile nu- using a window, which limits the neutron flux available clear material container. for the process. The direct interaction between the In another aspect of the present invention, in accor- proton beam and the sodium coolant will produce sub- 50 dance with its objects and purposes, the apparatus for stantial quantities of oxygen, carbon, nitrogen, and hy- transmuting higher actinide waste along with WC, 129X, drogen spallation products, which may combine to and other fission product waste may include a source of generate tar. Finally, degradation ofthe cladding mate- high intensity, high-energy of protons, a liquid-metal rial for [he nuclear waste as a result of proton bombard- spallation target having an upwardly facing open sur- ment may present a lifetime problem. In “Accelerator 55 face for producing a high neutron flux u~n being im- MoIten-Salt Breeding And Thorium Fuel Cycle,” by pacted by high-energy protons, a substantially gas-tight Kazuo Furukawa, Yasuaki Nakahara, Yoshio Kate, enclosure surrounding the spallation target, windowless Hicieo Ohno, and Kohshi Mitachi, Proceedings Of The apparatus for directing the beam of protons onto the 2trd International Symposium On Advanced Nuclear open surface of the spallation target, a neutron modera- Energy Research-Evolution By Accelerators, January 60 tor for thermalizing neutrons generated from the spall- 24-26, 1990, Mite, Ibaraki, Japan, the authors describe a ation target, and a container for holding the material to windowless apparatus accepting high proton beam cur- be transmuted located within the neutron moderator rents having GeV energies which are caused to impinge and spaced apart from and outside of the spallation directly on the target materials as in the Takada et al. target. reference except cooled by molten salt. Transmutation 65 In yet another aspect of the present invention, in is achieved using keV neutrons where the low cross accordance with its objects and purposes, the apparatus sections of the neutrons require large inventories to for simultaneously transmuting higher actinide mater- achieve useful transmutation throughput. Additionally, ialsand producing tritium may include: a source of high 5,160,696 d 4 intensity, high-energy protons, a liquid-metal spallation be converted rapidly. This can only occur in a high flux target having an upwardly facing open surface for pro- environment where resulting daughter products are ducing a high neutron flux upon being impacted by fissioned rapidly. Intense fluxes of low-energy neutrons high-energy protons, a substantially gas-tight enclosure also permit the rapid conversion of long-lived fission surrounding the spallation target, windowless apparatus 5 products such as technetium-99 which have small neu- for directing the beam of protons onto the open surface tron cross sections. Additionally, a2though the appara- of the spallation target, a neutron moderator for ther- tus of the present invention is expected to achieve malizing neutrons generated from the spallation target, yearly amounts of transmuted materials which are simi- a container for holding the higher actinide materiais lar to that from nuclear reactors or conventional accel- located within the neutron moderator and spaced apart 10 erator-based concepts, my invention requires less than from and outside of the spallation target, and a con- one-hundredth of the resident actinide or fission prod- tainer located within the neutron moderator and spaced uct materials than conventional apparatus. apart from the spallation target for holding materials Nuclear wastes are comprised of a relatively few which generate tritium upon interaction with neutrons. radioactive materials that cause most of the waste han- Benefits and advantages of the present invention in- 15 dling problems, Within this group are long-lived species clude power production from 2W-J, %%, and from having half-lives of 10,tMOto 2,000,000 years made up of burning defense and commercial higher actinide waste actinides such as neptunium-237, arnericium-241, and without long-term waste management, avoiding long curitrm-244, as well as fission products such as techneti- term management of commercial spent fuel by fission um-99 and iodine-129. Additional isotopes of concern product transmutation using ~39Pu from reprocessing 20 are shorter-lived species such as strontium-W and cesi- tritium production while burning higher actinide waste, um- 137 which have half-lives of approximate] y thirty 2W and 2J%. Another benefit of the present inven- years. Nuclear wastes stored at Department of Energy tion includes the avoidance of the major problem of sites are principal] y composed of such fission prcducts current nuclear reactors which is catastrophic runaway. with about 20% of higher actinides, while commercial Since the fission products can be continually removed 25 nuclear wastes are made up of more equal portions of from the molten salt stream and the inventory of frssile fission products and higher actinides, The defense material is small, the probability and consequences of a wastes generally exist in chemically partitioned forms loss-of-coolant accident also are significantly reduced, which is a prerequisite for introduction into a trsmsmu- The probability of such an accident is greatly reduced tation system. Commercial waste is in the form of undis- since this system operates well below nuclear criticality 30 turbed spent fuel, and requires no control rods. In a transmutation-based waste management strategy, Additional objects, advantages and novel features of actinides and fission products must be chemically sepa- the invention will be set forth in part in the description rated from bulk waste containing mostly stable and which follows, and in part will become apparent to short-lived nuclear species, The isotopes recovered in those skilled in the art upon examination of the follow- 35 this chemical processing can then be subjected to an ing or may be learned by practice of the invention. The intense accelerator-produced neutron flux having an objects and advantages of the invention may be realized energy spectrum optimized to produce rapid conver- and attained by means of the instrumentalities and com- sion rates. For fission products this means the use of binations particularly pointed out in the appended low-energy (thermal) neutrons where transmutation claims. 40 cross sections are large. Under such conditions, the long-lived fission products technetium-99 and iedine- BRIEF DESCRIPTION OF THE DRAWINGS 127 can be transmuted etlcientl y. Shorter lived species The accompanying drawings, which are incorpo- such as strontium-90 and cesium-137 can also, in princi- rated in and form a part of the specification, illustrate pal, be transmuted under such conditions. However, several embodiments of the present invention and, to- 45 their low reaction probabilities require intense neutron gether with the description, serve to explain the princi- fluxes for transmutation rates to compete with rates ples of the invention. In the drawings: associated with their natural decay. Finally, intense, FIG. 1 is a schematic representation of the proton low-energy neutron sources can transmute higher acti- accelerator which would provide high intensity, high- nides efficiently, as well. Using thermal neutrons, then, energy protons to a target in order to generate intense 50 a transmutation system which can efficiently handle neutron fluxes. defense wastes and commercial wastes will be de- FIG. 2 is a schematic representation of the power scribed, wherein the radiotoxicity of waste material generating, nuclear waste burning apparatus of the pres- prccessed can be reduced to a level no greater than the ent invention. natural radiotoxicity of the uranium that was consumed FIG. 3 illustrates the possible reaction and decay 55 in producing the wrote. Without transmutation, hun- paths for 2J7N’Pand 2AlAm, dreds of thousands of years would be required for these FIG. 4 is a schematic representation of the accelera- radioactive materials to decay to these levels. tor-based, high neutron flux production and reaction Beams of several nuclear particles such as protons, volume of the present invention. deuterons, alpha particles, etc. can be used to generate m neutrons from a liquid-metal spallation target such as a DETAILED DESCRIPTION OF THE Pb-Bi target. Without ruling out the others, it is be- INVENTION lieved that protons will be the simplest to accelerate and Recent advances in high-energy high current acceler- just as effective in the neutron generation process. A ator design permit high intensity sources of low-energy range of energies from 400 MeV to 10 GeV per nucleon neutrons based on accelerator-driven neutron spallation 65 would be usefuI, but 1.6 GeV has been selected as the to be envisioned. Fluxes of about one hundred times most effective proton beam energy. At 1.6 GeV, effec- greater than those found in standard nuclear reactor tive transmutation rates according [o the teachings of designs allow higher actinides such as neptunium-237 to the present invention require average beam currents of 5,160,696 5 6 at least 10 ma. Full-scale transmutation facilities might presented. A breeder reactor operating at a breeding require average currents in excess of 250 ma. ratio of 1.10 generates enough neutrons to produce as Reference will now be made in detail to the present much fuel as it consums, it also produces about one prefemed embodimems of the invention, examples of extra neutron per ten fissions, which might be used for which are illustrated in the accompanying drawings 5 several purposes including the breeder role of generat- Identical or substantially similar structure are identified ing 10% more fuel than it bums, The energy released in with lhe wrte callouts. FIG. 1 shows a schematic repre- production of this extra medium is 2C00 MeV thermal, senration of a 1.6 GeV, 250 ma linear accelerator 10 since 200 MeV is released in each fission. Comparing having an overall length of about 2090 meters intended this with the energy associated with accelerator-pro- for use in the apparatus of the present invention. It 10 duced neutrons of 150 MeV, we see an order-of-magni- includes beam injectors 12u,b, radiofrequenc y quad- tude difference. If we rake only 109o of the power from rupoles 14u,b for bunching the proton beam and accel- the breeder and convert it to neutrons using the acceler- erating it to 2.5 MeV, drift tube linacs Mu,b in which ator, we more than double the number of extra neutrons the beam is accelerated to 20 MeV, a funnel 18 to com- available, These extra neutrons, produced at little cost bime two 125 ma beams in order to reach the desired 15 to overall nuclear power electric energy efficiency, current, and a coupled cavity linac 20 to take the beam could be used for improving the breeding ratio, trans- to 1.6 GeV. Lower currents might be achieved by muting nuclear waste to stable or short-lived nuclei, avoiding the funnel and reducing the duty factor of the producing tritium, etc. sysrem. Other accelerator technology besides the radio- The argumenw presented here center around a spall- frequency lirsac might also be employed. 20 ation neutron.driven ~get surrounded by a blanket Transport of the beam from accelerator to target can containing material undergoing fission. Some of the be achieved with existing technology, and no novel blanket fission thermal energy is converted with high beam control or beam interruption devices need be efficiency to electric power and used to accelerate the developed. Beam loss in the accelerator and in the beam proton beam. An equation based on neutron economy transport can be held to sufficiently low levels that 25 only will now be presented which illustrates the impact remote maintenance will not be required. With routine of the spallation neutron process in defense and com- maintenance, the primary accelerator components are mercial nuclear energy technologies. expected to endure for at least thirty years. The acceler- The rate of change of the total number of neutrons in ator will be designed for greater than 90% up time. a system dn/dt is given by FIG. 2 is a schematic representation of the apparatus 30 of Lhepresent invention. Accelerator 10 provides a high dn/di=S+ mRf-(1 +a)Rp C-L- U (1) intensity, high-energy proton beam to reaclion appara- tus 40. Neutrons are generated in target 42 and thermal- where m is the average number of neutrons emitted per ized in moderator 44. The materials to be transmuted or fission in the primary fissile material, R~is the total rate fissioned are circulated through the moderator in recir- 35 of fission in the system of the fissiie material, and a is the ctdating loop 46, and the fission products separated capture-to-fission ratio for the fissile material. We de- therefrom in processor 48. Heat exchanger and electric fine each of the six terms on the right hand side of Eq. power generation means 50 extract heat from the reac- 1 below: tion assembly 40 and generate electricity therefrom, S—the total number ofspallation source neutrons intro- some of which may be used to power accelerator 10. 40 duced into the volume per second. The advantages of employing an accelerator can be mR@he product of the average number of neutrons based on very simple arguments. We start with the per fission times the fission rate in the system so that premise, considered fundamental, that there would be it is the total number of neutrons introduced into the no nuclear power if the average number of neutrons system by fission. emined per fission did not exceed one so that a chain 45 (1 + a)R~the number of neutrons used in the system to reaction was possible, and that the breeder would not be produce the fission from thermally fissile material. possible if this number of neutrons did not exceed two. The multiplying coefficient would be unity if all neu- However, with the introduction of the modem high tron absorption led to fission. However, since neu- current and high efficiency accelerators, nuclear power tron capture is present also, the loss of neutrons must becomes possible in principle even withoul the emission so be increased by the capture-to-fission ratio a. of neutrons in the fission process. Consider the energy C—the rate of conversion of fertile material to fissile cost of an accelerator-produced neutron. A 1600-MeV material by absorption of one neutron per converted proton wiIl produce about 55 neutrons upon striking a nucleus. Pb-Bi target. Assuming an accelerator driven target/- L—the rate of neutron loss in the system including blanket using molten salt breeder reactor (MSBR) tech- 55 leakage, absorption in control rods, and neutron cap- nology with a thermal.to-electtic conversion efficiency ture in system structural materials. of 4% and the expected bussbar efficiency of advanced U—the rate of absorption of the remaining neutrons for high current accelerators of 45?4, the energy cost of the useful purposes such as the bum-up of fssion prod- neutron is 1600/(55x0.45 xO.44)= 150 MeV. Since 200 Ucts. MeV is produced per fission, the accelerator can pro- 60 We are only interested in the situation where the thsce more than enough neutrons to maintain a sustained neutron production and absorption rates are balanced; reaclion rate in a fissile target such as ZJ5Uwithout any i.e., dn/dt = O.We rewrite the equation then in terms of fission neutron emission. The energy cost of a neutron the usefu! neutrons as drops to near lMI MeV if the proton beam strikes a uranium target so that even breeding is almost possible 65 U= S+mR/–(l +a)R/- C–L (2) without any fission neutron emission. Since a breeder reactor optimizes neutron economy, We will first illustrate the use of the equation in some an argument based on the physics of the breeder is next well-known reactor situations (requiring S =0) and then 5.160.696 7 8 move on to situations involving spallation neutrons, protons. Each of these protons produces about 50 neu- where S is non-zero. trons. For a fission rate R/ producing 0.200 GeV per fission, we may then write the spallation source term S A. NO SPALLATION NEUTRONS as 1. Thorium Thermal Breeder 5 S= R/x(0.2/l.6)x0.44 x0.45xJx50=l.24f R/ (5) The MSBR developed at ORNL for breeding Z33U from 232Th is one of the few successful thermal breed- Substituting for S we may rewrite Eq. 2 as ers. We use it as an example since our spallation system also uses molten salt as the working medium. The con- U= 1.24f Rf+mRj-(1 +a)Rj– C–L. (6) version (breeding) ratio for this system w= found to be 10 about 1.02. That is, for every 233U nucleus burned, Using Eq. 6 we can reconsider thermal breeding and 1.02(1+a) were created from the thorium. Therefore several other prospects for the acceleratordriven lead- the value for C= 1.02(1+a)R} Since the MSBR only bismuth molten salt target surrounded by a blanket with barely breeds, there are no neutrons left over for any 15 molten salt containing fissionable material, fertile mate- other purpose and we can then use Eq. 2 to =Iculate the rial, material to be transmuted, etc. loss term L. We have 1. Burning W-J Without Long-Term Fksion Product L/mR~ I - 2.02(1+u)/m (3) Storage For 233U we have m= 2.49 and a= O.0861 which give 20 For this example we use the neutrons to convert 2W_J L/mR~O. 13. Therefore, with the greatest effort to 2~9Puwith a continuous feed of 238u to the system so toward neutron conservation, the thermal MSBR still that the ratio of 239Pu to 23W is constant (a breeding loses 13% to leakage, parasitic capture and to the con- ratio of 1.tXl).This corresponds to C=(l +a)R~ Using trol rods. the value for L established above of L/mR~. 13 for the 25 molten salt system and the fission parameters for 239Pu 2. The ZWJ Thermal Breeder we find We nex[ consider the case of a conceptual 238(Jther- U/R~ 1.24J+m-2(l +a)-O.13m= 1.24/–0.217 (7) mal breeder producing ZJ9PUassuming the same loss rate L and ask for a breeding ratio of only unity to If we want no excess neutrons, we solve Eq. 7 with determine if breeding is possible. In this case Eq. 2 30 becomes U/R~O and find that we can bum Z3W by taking the fraction f=O. 175 of the electrical power from the tar- U/nrRp I –2,00(1 +u)/m –013 (4) get. If we wish to bum waste fission products created from the fission of 239Puat the rate necessary for man- For lJYPu we have m =2.877 and a =0.360 which give 35 agement for a time span comparable to one human life- U/mR/–O.O75. Therefore, the thermal system falls span, we require U/R~O.21. This means that only 7.5% short of the number of neutrons required for a 1/2 x21 %= 10.5% of the fission products need to be conversion ratio of unity and we arrive at the estab- transmuted in order to make practical managed storage lished knowledge that a thermal ZJ8U breeder is not over one human lifespan. From Eq. 7 we find f= O.344. practical. 40 The overall efficiency of the system for burning of Z~W with fission product destruction is 3. The ZWJ Fast Breeder 44%x (I .–0.344)=29% which is not far below the A fast breeder works on the principle that the capture electrical efficiency of commercial power reactors now cross section drops faster than the fission cross section on line. Therefore, the addition of the accelerator not as the neutron energy increases into the higher keV 45 only makes thermal burning of ZJWIpossible but allows region. Asking for a breeder with breeding ratio of 1.1, it to be burned with reasonable efficiency and with a we have, referring to Eq. 4, U/R~O. 1. If we assume waste stream which need be managed on]y over a tha~ the loss rate for the fast breeder is the same as that human lifespan. for the Z3ZT12thermal breeder and calculate a for ZJ9PU 2. Burning 2JzTh Without Long-Term Fission Product in the keV region, we find a 0.20 which in fact is the 50 value measured at a neutron energy of 60 keV which is Storage near the center of the fast neutron spectrum. The continuous circulation of the molten salt allows the 2JJPa generated from neutron capture in 232Thto be B. ADDING SPALLATION NEUTRONS separated on line before it is converted 10 Z34Uby ab- The above examples illustrate the use of the neutron 55 sorbing another neutron. The zlJPa can then be burned economy Eq. 2 and remind us that a thermal breeder after its beta decay to fissile ZJ3U. We use the same reactor alone provides essentially no excess neutrons. In equation as Eq. 7 with the parameters m and a given this section we add in spallation neutrons and show that above for 233u. The result is the addition of an accelerator makes a remarkable dif- ference in a thermal neutron system. We will consider 60 U/Rj= 1.24/- 0fK16 (8) the case where the accelerator is being operated by electric power derived from a target/blanket containing Therefore to bum thorium and its fission products, we material undergoing fission. The thermal power from insert U/R~ 0.21 in Eq. 8 and find f=O. 174. The over- the target/lianket is converted to electric power with all efficiency for burning thorium is the the etTciency projected for a large MSBR (44%). We 65 44% x(1 – O.174)= 36%. It is better than the efficiency pull out a fraction f of this electric power and use it to for Z3W because of the more favorable value for the power the accelerator, which has an overall efficiency capture-to-fission ratio for Z33U.Some of this e~ciency of 4570 for production of intense beams of 1.6 GeV can be traded off if necessary to increased neutron loss 5.160.696-, 9 10 by absorption in structural materials or simply to leak- effective way 10 burn the fission product waste using age from the system. the accelerator would be to bum in the blanket some of the ZJ9PUseparated from the spent fuel. The effective- 3. Burning the Higher Actinides Without Long Term ness of this can be obtained from ~. 6 also. For this Fission Product Storage 5 case, the conversion term is zero since the 239Puis itself Managing the waste generated in either the defense tissile material. Using the same loss term and the vafues or commercial sector is significantly influenced by de- for Z39PUof m=2.877 and a= O.360, we have struction of the higher actinides by fission. The destruc- tion of these actinides reduces [he storage time for tl/R~ 1.24J+1.14 (lo) decay of waste to innocuous radioactivity levels from 10 several hundred thousand years to several hundred Let us assume that we wish to bum as much fission years. The primary constituents in commercial waste product as possible so we set f = 1meaning that all of the 237NP ad 241Arn, both Of which normally require ~e target power is used to drive the accelerator. The re- the absorption of at least three thermal neutrons for sulting vahse for U/R/is 2.38 which means that 2.38 destruction by fission. However, in the presence of a 15 fission fragments can be burned for each fission event. high flux of about 1016n/cm~-s, the unstable “product” We know that long term storage can be avoided if we nuclides 238Np and 242Am can be burned before they transmute only the fraction U/R~O.21 of the fwion decay because of their extraordinarily high fission cross fragments Therefore, if we use the accelerator to drive sections. This is illustrated in FIG. 3 where nuclides in a 2J9Pufueled system, we can transmute the fkSiOn the transmutation path for 2JTNP and 241Am in a low 20 product waste at the ratio of 2.38/0.21=11.3. That is, neutron flux are shown along with fission and capture one accelerator/target system could transmute the fis- cross sections in barns denoted by f and c, respectively. sion products from 11.3 commercial power reactors For ~7Np the high ffux and high cross section of the operating at the same power level. product nucleus 23SNPa!lows most of it to be destroyed by neutron-induced fission before it decays to ZJSPU25 5. Tritium Production While Burning Actinide Waste with its 2.1 day half-life and proceeds further up the We have seen above that, with an accelerator, higher neutron capture chain. For 241Am, 90% of the neutron actinide waste can be burned with enough margin to captures lead to ground state 242Amwhich decays with a half-life of 16 hours. The remaining 10% of the cap- allow for burning of the fission products produced in tures produce the isomeric state 242mAmwhich has a the fission of the actinides and at the same time to allow 30 longer half-life. Both states of z4zAm have a very high the generation of electric power at an overall efficiency fission cross section and in a high flux most will undergo perhaps as high as 36%. Let us consider the production destruction by fission without further neutron capture of tritium by burning the high actinide defense waste to higher mass. With the high fhsx the number of neu- with all of the fission power being converted to electric trons required for destruction of 2J7Np and 2d1Am by power for driving the accelerator. Using Eq. 9 with 35 fission at 2J8NP and 242Am is substantially less than if f= 1, we find U/RP 1.01. One neutron is produced for decay aflowed them to proceed farther up the neutron transmutation for every higher actinide waste nuclide capture chain. In this high flux situation, the number of which undergoes fission. For an acceleratordriven source neutrons required for fission is therefore reduced target operating at a power level of 3000 MWT, the and an appropriately designed system will actually ex- fission rate (and therefore the useful neutron production 40 hibit neutron multiplication owing to fission neutron rate) is 9.4x 1019/s. This translates to a tritium produc- emission. tion rate of 12 kg/yr if each neutron is absorbed on 3He The effectiveness of burning actinide waste may be or bLi. This prospect allows for the production of a illustrated for z37Np using Eq. 6 assuming a value for substantial amount of ts-itium while burning defense the average number of neutrons emitted per fission m of program higher actinide waste, transmuting the fission 2.70 midway between that for 2J5u and 239Pu. The 45 products resulting from fission of the higher actinide value taken for a of 0,29 is the same as that for ~4ZmAm, waste so as to avoid long term storage, and perfomting which is the only odd-odd nucleus measured. We as- these functions without drawing power from the com- sume that the flux is high enough that none of the 2JgNp mercial grid. An inspection of Eq. 7 reveals that the decays before the second neutron absorption. We find same tntium production rates can be produced by bur- 50 ningZWJ if a31blanket power is returned to the accelera- Wf?p 1.24J-0,231 (9) tor. Consideration of Eq. 8 shows that the tntium pro- duction rate using zJzTh as fuel is more effective than For the bum up of the fission fragments we require 23SUby about 25~0 since the value of a for 233Uis more excess neutrons at the rate of U/R~O.21. Solving Eq. favorable than that for z~gPu. 9 for f, we find that the fraction 0.186 of the electric 55 Having generally described the invention, the follow- power generated must be diverted to the accelerator. ing examples are intended to more particularly illustrate The anaIysis indicates that higher actinide waste can be spec itic features thereof. burned with the generation of electric power at an etT]- ciency of 44%(1 –0.186)=36$7.. EXAMPLE I 60 4. Burning Fksion Products Using 2J9Pu as the Fuel Energy Production Using Fertile Fuels: Commercial nuclear power reactors produce higher The increase in neutrons per fission associated with actinide “’waste” which we see above can be burned the introduction of the accelerator and spallation target with the accelerator at high efficiency without a fission according to the teachings of the present invention product waste stream requiring long term storage. In 65 opens the possibility for fission energy production from addition, they produce fission products which can be the fertile materials zszTh and ZWJ while also burning transmuted to material which need be stored only for the actinide and fission product waste. The important periods comparable to the human lifetime. The most details of the reactor apparatus 40 shown in FIG. 2 5,160,696 11 12 hereof which accomplish this purpose are illustrated in second molten salt loop dedicated to waste burning. For FIG. 4. Proton beam 80 enters a windowless beam drift these fertile fuels there would be no actinide waste tube 82 which makes a substantially vacuum tight seal stream as usually associated with power production with enclosure 84 which is part of a heat exchanger from fissile materials. Product actinides may be left in 86/recirculating loop 88 for removing heat from the 5 the molten salt loop where their concentration will liquid-metal spallation targel. At the high proton beam grow to an equilibrium concentration in which all acti- intensities contemplated for practicing the present in- nides heavier than the primary fissile nuclide will be vention it is essential that windows be eliminated from burned as fast as they are produced. This concentration the proton delivery system. Drift tube 82 is cooled and will have negligible impact on the blanket performance. pumped (apparatus not illustrated) in order to maintain 10 The operation of the system for ZJzTh and 2WJ will the high vacuum conditions required for generation and have one substantial difference. The 232TIIsystem will transmission of protons. Shown is a lead-bismuth eutec- require the continuous removal of zJ~Pa which is gener- tic mixture liquid-metal spallation target. Also illus- isted following decay of the zj~ll produced by thermal trated is normally-closed valve 90 which drains enclo- neutron capture of ZJzTh. When removed from the sure 84 and heat exchanger/recirculating loop 86,88 15 neutron flux, this material naturally decays to highly into reservoir 92 in the event that a predetermined con- fissile 233Uwith a half-life of 27 days. The 23ZJ is then dition cccurs. It should be mentioned at this point that returned to the molten s.dt loop where it is burned by the spallation products formed in the target eventually the neutron flux to produce nuclear energy. If the ZJJPa are substantially transmuted back toward lead in the is allowed to remain in the neutron flux, it will capture high neutron flux environment. Neutrons emerging 20 a second neutron and be transmuted to 2~Pa which from enclosure 84 are moderated by moderator 44 for then decays quickly to z~U which is not fissile with which heavy water is suitable. Molten salt recirculation thermal neutrons. For 238U, this step of continuous loop 94 contains the fertile or fissile materials and fission removal might not be required since in a 1016n/cmz-s products thereof, and perhaps a tntium precursor, if flux, 85% of the Z39Uproduced by the capture of a first tritium is to be generated. Heat exchanger % removes 25 neutron decays to 139Pu before capture of a second heat from loop 94 and together with heat exchanger 86 neutron. The percentage can be increased still further may be used to power heat exchanger/electric power by placement of the salt in the outer portions of the generation means 50 shown in FIG. 2 hereof. As will be blanket where the flux has decreased substantially. The discussed below, fission products are separated from inner portion of the blanket would be devoted princi- recirculation loop 94 by processor 48 also shown in 30 pally to fission product burning in the higher flux. The FIG. 2 hereof. After further separation of the stable and 2JlTh overall energy efficiency is substantial] y higher short-half-life species, waste materials to be transmuted than that for 23*U because the capture-to-fission ratio are inserted into containment means 98 for further irra- for the product nucleus ZJW is more favorable than that diation. Containment means 98 are located closer to the for the corresponding 239Pu nucleus. liquid-metal target enclosure 84 in order to take advan- 35 The comparison between established reactor technol- tage of the somewhat higher neutron flux found in the ogy and the accelerator-based system is worth noting. vicinity thereof. A proposed composition for the molten The number of neutrons per fission is barely su~cient salt eutectic might be a ratio of 5270 by molecular to make possible practical breeder reactors for either weight of 7LiF to 48% of BeFz for the transporf of z31Th or ZJSU.It is not practical to bum the waSte from dissolved fluorine salts of the actinides or of fission 40 a breeder in addition since, as stated, there are no extra products into and out of the recirculation loop. An neutrons available; any extra neutrons available being alternative composition might be 2770 UF4 and 73% expended in the breeding process. Therefore, while 7L1F. Another function of processor 48 is to Illahtaln burning the full thorium and uranium resource is now the ion/fluoride balance in the recirculation loop. The practical with breeder reactors, it is not possible to bum 45 overall efficiency for energy production depends upon their waste to avoid repository storage for long time the fraction of the electricity generated which must be periods. This is true whether one attempts to bum the returned to the accelerator to supplement the neutron waste in the breeder itself or in a separate waste-burner economy. This efficiency is therefore significantly im- reactor fueled by the excess frssile material bred. In proved by taking advantage of the high therrnal-to-elec- either situation, the excess neutrons per fission are insuf- 50 tnc conversion efficiency of 4470 possible owing to the ficient. However, in the accelerator-target/bkartket-tur- high operating temperature of the molten salt, the state- bme system of the present invention, the full uranium of-the-art accelerator bussbar-to-beam etTciency of and thorium resource can be burned with reasonable 45-50%, the reduction to the degree possible of neutron efficiency and without a waste stream which must be loss to leakage and capture in the target/blanket compo- managed for periods well beyond the human lifespan. 55 nents, and the transmutation of as little of the waste as The accelerator-based system has the additional advan- possible consistent with the waste elimination objec- tages that the blanket is subcritical and contains orders tives. of magnitude less actinide material which might be The objective in burning the waste is to reduce the dispersed in the event of an accident. time for storage and management of the waste to a time period comparable to the human lifespan. This would 60 EXAMPLE II be accomplished by continuous removal of the fission Burning Commercial Nuclear Waste products from the molten salt by means of a slip stream. The fission products would be separated into three Spent reactor fuel elements are placed in pools for groups: the stable products, which would only be made long storage periods during which the radioactivity radioactive by further irradiation, those which naturally 65 decays to substantially lower levels compared to that decay to the radioactivity level of uranium ore in about when initially removed from the reactor. Burning this eighty years, and the longer half-lived products. The waste requires that the fuel be chemically partitioned latter materials would by returned to the blanket in a into the following components: 5,160,696 13 14 1.Residual uranium (potential fertile material); waste should be in a waste burning loop and the actinide 2. Plutonium isotopic mixture (potential fuel); waste should be in a primary fuel loop. 3. FOgher actinides such as lj7Np adn 241Am, and Any of the four fuels listed hereinbelow in Example other fission products having long half-lives; IV or a combination thereof may be used. For maxi- 4 Wsr and 137Cs;and 5 mum effectiveness, all electric power generated in the 5. Stable and short-lived fission products. system would be fed to the accelerator. Of course, the The most difficult materials to bum are the %r and system could be operated with all power coming from 137cs since three materials have the srnai]est cross sec. external sources. The waste material in the fission prod- tions. They must be burned in a flux of at least 1x 1016 uct loop which has been transmuted to stable or short- n/cm2-s if the destruction rate is to substantially exceed IO lived material would be removed continually using a that of the natural decay associated with their 30-year slip stream. Fission products would be removed from half-lives. Since these materials also constitute a large the fuel loop and after appropriate chemical separations, part of the fission product waste, there is much to gain returned to the fission product loop as set forth in Ex- from allowing the material to decay for a sixty year ample I. By high pm-ity chemical separations and recy - period, for example, in order to reduce the amount of 15 cling, the radioactivityy level of the waste could be re- material which must be transmuted to about one-fourth duced to a level below that of the original uranium ore. of its original value. At that point, the remaining mate- EXAMPLE IV rial would be cycled through the high neutron flux followed by chemicaI separation, and then repeatedly Tritium Production recycled for a period of about ten years until the mate- 20 An accelerator-based system for tritium production t-b] is reduced to the desired level of radioactivity. can be constructed which generates its own electric The higher actinide mixture bums readily by the power and which bums its own waste so that waste two-step process of the present invention in an intense management is necessary only over a time comparable flux of neutrons with a net supplement to the neutron to a human lifespan. In this situation, the tritium is pro- eccmomy rather than a depletion. Since the short-lived 25 duced by transmutation of 6Li by a (n,A) reaction to an and stable fission products need not be burned, the latter alpha particle and a tritium nucleus. The fJL\is present potentially being made radioactive by further irradia- in the molten salt mixture as LiF. The produced tritium tion, the remaining group, referred to as other fission is carried in the molten salt as tritium fluoride and is products having long half-lives, which constitutes the so removed continuously by use of a slip stream in the largest component of the waste to be burned, needs molten salt system. Such a system could be fueled with attention. In almost all situations, this material is con- 1. separated WJ, 2. with any excess 239Pu available in verted to stable or short-lived materials with the cap- the defense program, 3. with higher actinide waste ex- ture of a single neutron. In order to supplement the isting in the defense program, or 4. with the fertile mate- neutrons produced by the accelerator, it is helpful to 35 ria)s 232Th and 23sU. Of course, any combination of also bum some of the plutonium isotopic mixture. With these four is also possible. If fertile materials are present, this approach to waste burning, managed transmutation the fuel management program described in Example I and storage over a period comparable to the human must be employed. lifespan will result in a reduction of the radioactivity of The efficiency of production per fission decrm in the waste to a level comparable to the radioactivity of ~ the order of the four fuel materials listed above. To the original uranium ore. By supplementing the acceler- obtain the maximum tritium production rate, all of the ator-produced neutrons with the neutrons from pluto- electric power generated would be fed back into the nium burning, the waste from about ten commercial accelerator for any of the fueling options. The third power reactors can be burned with one target/blanket option has the advantage that tritium could be produced operating at the same thermal power as the reactor, 45 using defense actinide waste as fuel. The difference in while providing all electric power from the system the fourth option and power production from the ura- which is required to power the accelerator. nium and thorium resource as described in Example I is The plutonium mixture and the higher actinide waste that tbe fraction of the neutrons expended in producing wouId be burned in a primary molten salt loop with the fission energy which is fed into the power line is continuous removal of the fission products. The fission 50 instead used for conversion of the bLi to trkium. products requiring further transmutation would be The accelerator-based approach of the present inven- burned in a second loop located in the region of the tion for tritium production may be compared with pro- most intense neutron flux, as described hereinabove, duction using a reactor fueled with 235U, which has after being separated into the three fission product been the method of choice in the past and is planned for groups. . 55 the future. With the accelerator, the system would be EXAMPLE 111 operated far below criticality, there is no long-temr waste stream, and the inventory of fission products and Burning Defense Nuclear Waste actinide is lower by several orders of magnitude in case High-1evel defense waste includes fission products of an accident. The accelerator-driven process of the waste and higher actinide waste which is dominated by 60 present invention has the additional advantage that it 237NP, me Wrote h~ in almost al] situations been chem- can be fueled by four methods, one of which allows the ically processed and stored. In order to bum such waste elimination of an important component of the defense it must be retrieved from the storage tanks and chemi- waste, and another which avoids burning of the two caI1y processed into fluoride or other salts in order that iissile materials zJ~U and ZJ9PU, it be introduced into the molten salt loop of the present 65 The foregoing description of the preferred embodi- invention dedicated to waste burning. Both types of ments of the invention has been presented for purposes waste may be burned simultaneously in whatever ratio of illustration and description. It is not intended to be appears to be appropriate except that the fission product exhaustive or to limit the invention to the precise form 5,160,696 1s 16 disclosed, and obviously many modifications and varia- 8. The apparatus as described in claim 1, wherein said tions are possible in light of the above teaching. The high intensity, high-energy proton beam generation embodiments were chosen and described in order to means, said spallation target, and said neutron modera- best explain the principles of the invention and its prac- tion means produce a thermal neutron flux sufficient to tical application to thereby enable others skilled in the 5 permit substantial two-neutron transmutation processes art to best utilize the invention in various embodiments to occur in waste products resulting from producing and with various modifications as are suited to the par- power from the fertfle nuclear material. ticular use contemplated. It is intended that the scope of 9. The apparatus as described in claim 1, further com- the invention be defined by the claims appended hereto. prising second heat exchanger means for removing heat What I claim is: 10 from the flowing molten salt eutectic and fertile nuclear 1. An apparatus for producing power from fertile material combination after the combination pas= nuclear materials and transmuting wastes therefrom to through said neutron moderation means. less radioactive species, said apparatus comprising in 10. The apparatus as described in claim 9, further combination: comprising power generation means for generating a. means for generating a high intensity, high-energy 15 electricity from heat removed by either or both of said beam of protons; fmt heat exchanger means and said second hear ex- b. a liquid-metd spallation target having an upwardly changer means, and for returning a portion of the elec- facing open surface for producing a high neutron tricity to said high intensity, high-energy proton beam flux upon being impacted by high-energy protons; generation marts. c. a substantially gas-tight enclosure surrounding said 20 11. The apparatus as described in claim I, whereirr spallation target; said windowless means for directing the high intensi~y, d. windowless means for directing the beam of pro- high-energy proton beam into said spallation target tons onto the open surface of said spailation target; means includes a cooled, evacuated beam transpofi tube e. neutron moderation means for thermalizing neu- having one end thereof forming a substantially gas-tight trons generated from said spallation target; 25 seal to said gas-tight enclosure and disposed substan- f. first means for containing the fertile nuclear mate- tially vertically above said spallation target, the other rial disposed within said neutron moderation means end thereof forming a substantially gas-tight seal with and spaced apart from and outside of said spallation target; said proton beam generating means; whereby volatile gases produced within said spa21ationtarget means may g. second means for containing materials to be trans- 30 muted disposed within said neutron moderation be removed from the vicinity of the high intensity, means and spaced apart and outside of said spall- high-energy proton beam, and whereby the high inten- ation target, yet closer thereto than said first con- sity, high-energy proton beam may be directed substarr- tainment means; tially vertically and directly onto the open surface of h. first flowing means for passing the fertile nuclear 35 said liquid-metal spallation target. material and transmutation products thereof 12. The apparatus as described in claim 5, wherein through said first containment means; said gas-tight enclosure further comprises a convection i. means for combining the fertile nuclear material air-cooled holding tank located below said first heat with a molten salt eutectic and causing the combi- exchanger means into which the liquid-metal may drain, nation formed thereby to flow throu~h said first 40 and normally-closed valve means responsive to a flowing means; and chosen operating condition demanding that said valve j. means for extracting fission products from the mol- means be opened, thereby permitting the liquid metal to ten salt eutectic flowing through said first flowing drain out of said first heat exchanger means and out of means, separating the stable and short-lived fission the region of said spallation target. products therefrom, and introducing the remaining 45 13. The apparatus as described in claim 1, further material into said second containment means for comprising means for sensing and maintaining the ion/- transmutation. fluoride valence balance in the molten salt eutectic. 2. The apparatus as described in claim 1, wherein the 14. The apparatus as described in claim 1, further fertile nuclear materials are selected from the group comprising means for continuously removing zJ3Pa consisting of ZW, ZJzTh, and mixtures thereof. 50 from the molten salt eutectic !lowing through said tlow- 3. The apparatus as described in claim 1, wherein said ing means in the event 232TIIis utilized as a ferti3e mate- spallation target includes high-Z material for produc- rial. tion of neutrons by interaction with the high-energy 35. The apparatus as d=ribed in claim 1, further beam of protons. comprising second flowing means for passing the fission 4. The apparatus as described in claim 3, wherein said 55 products through said second containment means. liquid-metal spallation target includes a lead-bismuth 16. An apparatus for producing power from fissile eutectic mixture. nuclear materials without necessity for long-tenrr nu- 5. The apparatus as described in claim 4, further com- clear waste management, said apparatus comprising in prising first heat exchanger means through which the combination: liquefied lead-bismuth eutectic is circulated in order to 60 a. means for generating a high intensity, high-energy remove generated heat. beam of protons; 6. The apparatus as described in claim 1, wherein said b. a liquid-metal spallation target having an upwardly high intensity, high-energy proton beam generation facing open surface for producing a high neutron means provides protons having energies between 400 flux upon being impacted by high-energy protons; MeV and 10 GeV with an average proton beam current 65 c. a substantially gas-tight enclosure surrounding said of greater than 10 ma. spallation target; 7. The apparatus as described in claim 1, wherein said d. windowless means for directing the beam of pro- neutron moderation means includes heavy water. tons onto the open surface of said spallation target; 5.160.696. . 17 18 e.neutron moderation means for thermalizing neu- having one end thereof forming a substantially gas-tight trons generated from said spallation target; seal to said gas-tight enclosure and disposed substan- f. firstmeans for containing the fissile nuclear materi- tially vertically above said spallation target, the other als disposed within said neutron moderation means end thereof forming a substantially gas-tight sd with and spaced apart from and outside of said spallation 5 said proton beam generating means; whereby volatile target; gases produced within said spallation target means may g. second means for containing material to be trans- be removed from the vicinity of the high intensity, muted disposed within said neutron moderation high-energy proton beam, and whereby the high inten- means and spaced apart and outside of said spall- sity, high-energy proton beam may be directed substan- ation target, yet closer thereto than said first con- 10 tially vertically and directly onto the open surface of tainment means said liquid-metal spallation target. h. first flowing means for passing the fissile nuclear 27. The apparatus as described in claim 20, wherein material and transmutation products thereof saidgas-tight enclosure further comprises a convection through said first containment means; air-cooled holding tank located below said first heat i. means for combining the fissile nuclear material IS exchanger means into which the liquid-metal may drain, with a molten salt eutectic and causing the combi- and normally-closed valve means responsive to a nation formed thereby to flow through said first chosen operating condition demanding that said valve flowing means; and means be opened, thereby permitting the liquid metal to j. means for extracting fission products from the mol- drain out of said first heat exchanger means and out of ten salt eutectic flowing through said first flowing 20 the region of said spallation target. means, separating the stable and short-lived fission 28. The apparatus as described in claim 16, further products therefrom, and introducing the remaining comprising means for sensing and maintaining the ion/- material into said second containment means for fluoride valence balance in the molten salt eutectic. transmutation. 29. The apparatus as described in claim 16, wherein 17. The apparatus as described in claim 16, wherein 25 said first fissile nuclear material containment means the fissile nuclear materials are selected from the group contains a sub-critical inventory of fissile material. consisting of 2W.J, Z39PU,and mixtures thereof. 30. The apparatus as described in claim 1, further 18. The apparatus as described in claim 16, wherein comprising second flowing means for passing the fission said spallation target includes high-Z material for pro- duction of neutrons by integration with the high-energy 30 products through said second containment means. beam of protons. 31. An apparatus for transmuting higher actinide 19. The apparatus as described in claim 18, wherein waste along with 9WC, 1291,and other fission product waste, thereby eliminating necessity fOr 10ng-tetTt nu- said liquid-metal spallation target includes a lead-bis- muth eutectic mixture. clear waste storage, said apparatus comprising in com- 20, The apparatus as described in claim 19, further 35 bination: comprising first heat exchanger means through which a. means for generating a high intensity, high-energy the liquefied lead-bismuth eutectic is circulated in order beam of protons; to remove generated heat. b. a liquid-metal spallation target having an upward] y 21. The apparatus as described in claim 16, wherein facing open surface for producing a high neutron said high intensity, high-energy proton beam generation 40 flux upon being impacted by high-energy protony means provides protons having energies between 400 c. a substantially gas-tight enclosure surrounding said MeV and 10 GeV with an average proton beam current spallation target; of greater than 10 ma. d. windowless means for directing the beam of pro- 22. The apparatus as described in claim 16, wherein tons onto the open surface of said spallation target; said neutrori moderation means includes heavy water. 45 e. neutron moderation means for thermalizing neu- 23. The apparatus as described in claim 16, wherein trons generated from said spallation target; and said high intensity, high-energy proton beam generation f. first means for containing the material to be trans- means, said spallation target, and said neutron modera- muted disposed within said neutron moderation tion means produce a thermal neutron flux sufficient to means and spaced apart from and outside of said permit substantial two-neutron transmutation processes 50 spaliation target; to occur in waste products resulting from producing g. second means for containing material to be trans- power from the fissile nuclear material. muted disposed within said neutron moderation 24. The apparatus as described in claim 16, further means and spaced apart and outside of said spall- comprising second heat exchanger means for removing ation target, yet closer thereto than said first con- heat from the flowing molten salt eutectic and fissile 55 tainment means; nuclear material combination after the combination h. first flowing means for passing the material to be passes through said neutron moderation means. transmuted and transmutation producs thereof 25. The apparatus as described in claim 24, further through said first containment means; comprising power generation means for generating i. means for combining the material to be transmuted electricity from heat removed by either or both of said 60 with a molten salt eutectic and causing the combi- first heat exchanger means and said second heat ex- nation formed thereby to flow through said first changer means, and for returning a portion of the elec- flowing mean% and tricity to said high intensity, high-energy proton beam j. means for extracting transmutation products from generation means. the molten salt eutectic flowing through said first 26. The apparatus as described in claim 16, wherein 65 flowing means, separating the stable and short- said windowless means for directing the high intensity, lived fission products therefrom, and introducing high-energy proton beam into said spallation target the remaining material into said second contain- means includes a cooled, evacuated beam transport tube ment means for transmutation. 5,160,696 , 19 Au 32. The apparatus as described in claim 31, wherein 44. The apparatus as described in claim 31, wherein a the higher actinide materials are selected from the chosen quantity of 239Pu is added to the molten salt group consisting of 2~7Np,241Am, l~m, and mixtures eutectic to generate sufficient heat to power said proton thereof. beam generating means, and to provide additional nett- 33. The apparatus as described in claim 31, wherein 5 trons, while maintaining sub-criticality. said spallation target includes high-Z material for pro- 45. The apparatus as described in claim 31, further duc~ion of neutrons by interaction with the high-energy comprising second flowing means for passing the fission beam of protons. products through said second containment means. 34 The apparatus as described in claim 33, wherein 46. An apparatus for simukarteously transmuting said liquid-metal spallation target includes a lead-bis- 10 higher actinide materials and producing tritium without muth eutectic mixture. necessity for Iortg-temr nuclear waste storage, said ap- 35. The apparatus as described in claim 34, further paratus comprising in combination: comprising first heat exchanger means through which a. means for generating a high intensity, high-energy the liquefied lead-bismuth eutectic is circulated in order beam of protons; to remove generated heat. 15 b. a liquid-metal spallation target having an upwardly 36. The apparatus as described in claim 31, wherein facing open surface for producing a high neutron flux upon behtg impacted by high-energy protons; said high intensity, high-energy proton beam generation means provides protons having energies between 400 c. a substantially gas-tight enclosure surrounding said spallation target; MeV and 10GeV with an average proton beam current 20 d. windowless means for directing the beam of pro- of greater than 10 ma. tons onto the open surface of said spaflation target; 37. The apparatus as described in claim 31, wherein e. neutron moderation means for themralizing neu. said neutron moderation means includes heavy water. trons generated from said spallation target; 38. The apparatus as described in claim 31, wherein f. first means for containing the higher actinide mate- said high intensity, high-energy proton beam generation 25 rials disposed within said neutron moderation means, said spallation target, and said neutron modera- means and spaced apart from and outside of said tion means produce a thermal neutron flux sufficient to spallation target; and permit substantial two-neutron transmutation processes g. means disposed within said neutron moderation to occur in the material to be transmuted. means and spaced apart from said spallation target 39. The apparatus as described in claim 31, further 30 for holding materials which generate tntium upon comprising second heat exchanger means for removing interaction with neutrons; heat from the flowing molten salt eutectic and material h. second means for containing material to be trans- to be transmuted combination after the combination muted disposed within said neutron moderation passes through said neutron moderation means. means and spaced apart and outside of said spall- 40. The apparatus as described in claim 39, further 35 ation target, yet closer thereto than said first con- comprising power generation means for generating tainment means; electricity from heat removed by either or both of said i. first flowing means for passing the higher actinide first heat exchanger means and said second heat ex- materials to be transmuted and transmutation prod- changer means, and for returning a portion of the elec- ucts thereof through said first containment means; tricity to said high intensity, high-energy proton beam 40 j. means for combining the higher actinide materials generation means. to be transmuted with a molten salt eutectic and 41. The apparatus as described in claim 31, wherein causing the combination formed thereby to flow said windowless means for directing the high intensity, through said first flowing means; and high-energy proton beam into said spallation target k. means for extracting transmutation products from means includes a cooled, evacuated beam transport tube 45 the molten salt eutectic flowing through said tirst having one end thereof forming a substantially gas-tight flowing means, separating the stable and short- seal to said gas-tight enclosure and disposed substan- lived ftssion products therefrom, and introducing tially vertically above said spallation target, the other the remaining material into said second contain- end thereof fonrsing a substantially gas-tight seal with ment means for transmutation. said proton beam generating means; whereby volatile 50 47. The apparatus as described in claim 46, wherein gases produced within said spallation target means may the higher actinide materials are selected from the be removed from the vicinity of the high intensity, group consisting of 237NP, 241Am, 2*m, and mixtures high-energy proton beam, and whereby the high inten- thereof. sity, high-energy proton beam may be directed substan- 4S. The apparatus as describe in claim 46, wherein the tially vertically and directly onto the open surface of 55 materials which generate tritium upon interaction with said liquid-metal spallation target. neutrons are selected from the group consisting of jHe, 42. The apparatus as described in claim 35, wherein 6Li, and ~xtures thereof. said gas-tight enclosure further comprises a convection 49. The apparatus as described in claim 46, wherein air-cooled holding tank located below said first heat said spallation target includes high-Z material for pro- exchanger means into which the liquid-metal may drain, 60 duction of neutrons by integration with the high-mergy and normally-closed valve means responsive to a beam of protons. chosen operating condition demanding that said valve 50. The apparatus as described in claim 49, wherein means be opened, thereby permitting the liquid-metal to said liquid-metal spallation target includes a lead-bis- drain out of said first heat exchanger means and out of muth eutectic mixture. the region of said spallation target. 65 51. The apparatus as described in claim 50, further 43. The apparatus as described in claim 31, further comprising first heat exchanger means through which comprising means for sensing and maintaining the ion/- the liquefied lead-bismuth eutectic is circulated in order fluoride valence balance in the molten salt eutectic. to remove generated heat. 5,1$0,696 Al 22 52. Theappara;us asdescribed in claim 46, wherein having one end thereof forming a substantially gas-tight said high intensity, high-energy proton beam generation seal to said gas-tight enclosure and disposed substan- means provides protons having energies between 4CQ tially vertically above said spallation target, the other MeVand 10 GeVwith anaverage proton beam current end thereof forming a substantially gas-tight seal with of’greater than 10 ma. 5 said proton beam generating means; whereby volatile 53. The apparatuses described in claim 46, wherein gases produced within said spallation target means may said neutron moderation means includes heavy water. be removed from the vicinity of the high intensity, 54. Theapparatus asdescribed in claim 46, wherein high-energy proton beam, and whereby the high inten- said high intensity, high-energy proton beam generation sity, high-energy proton beam may be directed substan- means, said spallation target, and said neutron modera- 10 tially vertically and directly onto the open surface of tion means produce athermal neutron flux sufficient to said liquid-metal spallation target. permit substantial two-neutron transmutation processes 58. The apparatus as described in chim 51, wherein to occur in the higher actinide materials. said gas-tight enclosure further comprises a convection 55. The apparatus as described in claim 46, further air-cooled holding tank located below said ftrst heat rxrmprising second heat exchanger means for removing 15 heat from the flowing molten salt eutectic and higher exchanger means into which the liquid-metal may drain, actinide materials combination after the combination and normally-closed valve means responsive to a passes through said neutron moderation means. chosen operating condition demanding that said valve 56. The apparatus as described in claim 55, further means be opened, thereby permitting the liquid metal to comprising power generation means for generating 20 drain out of said first heat exchanger means and out of electricity from heat removed by either or both of said the region of said spallation target. first heat exchanger means and said second heat ex- 59. The apparatus as described in claim 46, further changer means, and for returning a portion of the elec- comprising means for sensing and maintaining the ion/- tricity to said high intensity, high-energy proton beam fluoride valence balance in the molten salt eutectic. generation means. 25 60. The apparatus as described in claim 46, wherein 57. The apparatus as described in claim 46, wherein sutXcient Z39PUis added to the moIten salt eutectic to said windowless means for directing the high intensity, generate sufficient heat to power said proton beam high-energy proton beam into said spallation target generating means, and to provide additional neutrons. means includes a cooled, evacuated beam transport tube ***** 30 35 40 45 50 55 60 65